Laser & Photonics Reviews

A microcavity laser with a notched elliptical resonator produces a highly collimated unidirectional emission from optical whispering-gallery modes. Shown is the simulated optical intensity distribution inside and around the laser cavity. (Picture: N. Yu, Q. Wang, F. Capasso, pp. 23–46, in this issue)

A review of the complexity development of InP-based Photonic ICs is given. Similarities and differences between photonic and microelectronic integration technology are discussed and a vision of the development of photonic integration in the coming decade is given.

The paper reviews progress and future prospects of two kinds of planar waveguide devices; they are (a) silica and silicon photonics multi/demultiplexers for communications and signal-processing applications, and (b) a novel waveguide spectrometer based on Fourier transform spectroscopy for sensing applications.

Two approaches of beam engineering of mid-infrared and terahertz quantum cascade lasers (QCLs) are reviewed: designer plasmonic structures and deformed microcavities. The plasmonic structures couple laser emission into surface waves and control the laser wavefront in the nearfield, thereby greatly increasing beam collimation or introducing new functionalities to QCLs. The deformed microcavity QCLs operate primarily on whispering-gallery modes, which have much higher quality factors than other modes, leading to lower threshold current densities.

The current state-of-the-art in silicon nanophotonic ring resonators is reviewed. The basic theory of ring resonators is discussed, and applied to the peculiarities of submicron silicon photonic wire waveguides: the small dimensions and tight bend radii, sensitivity to perturbations and the boundary conditions of the fabrication processes. Theory is compared to quantitative measurements. Finally, several promising applications of silicon ring resonators are discussed.

Today, coupled resonator optical waveguides (CROWs) are conceived as a new way to guide light on a photonic chip. Controlling chains of coupled resonators to let light propagate through, with a reduced speed and enhanced intensity, boosting light-matter interaction while keeping information undistorted: this is the fascinating promise of CROWs, but also one of the most ambitious challenges ever set for integrated optics. Here, design criteria and management issues, fundamental limits, and sensitivity to fabrication tolerances are discussed.

Progress in developing photonic chip based optical processing devices with ultrahigh-bandwidth is reviewed. The unprecedented processing bandwidth of our platform based on dispersion engineered chalcogenide waveguides is exploited to perform Tbaud optical switching and performance monitoring. Recent experiments and demonstrations of photonic logic operations are reviewed.

Applications of Integrated Optics to quantum sources, detectors, interfaces, memories and linear optical quantum computing are described in this review. By their inherent compactness, efficiencies, and interconnectability, many of the demonstrated individual devices can clearly serve as building blocks for more complex quantum systems that could also profit from the incorporation of other guided wave technologies.